Photographic dry mounting tissue



Patented mo par M Arthur W. M. Dickins and Neil S. Kocher, Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N. Y., a corporationof New York No Drawing. Application September 18, 1933, Serial No.689,876

2 Claims.

I'his invention relates to dry mounting tissue, such as is used inmounting photographic prints on cardboard or on the leaves of albums,etc., by means of heat and pressure. One' object of our 5 invention isto provide a dry mounting tissue which will be satisfactory for use evenafter prolonged storage. Another object is to provide a dry mountingtissue which can be used at a moderate temperature and over a fairlywide range of temperature. Other objects will hereinafter appear.

The use of dry mounting tissue for mounting photographic prints is wellknown in the art. The dry mounting tissue in common use consists of thintissue paper impregnated with shellac. The tissue is placed between theback of the photographic print and the cardboard or paper surface onwhich it is desired to mount the print, and the whole assemblage issubjected to heat and pressure, for instance by means of a warmflat-iron. This has the eifect of softening the shellac and causing themounting tissue to adhere to both the print and the mount, thus mountingthe print without the warping which is liable to occur when paste orglue is used. However, the shellac-impregnated paper deteriorates duringstorage and becomes useless, and it is, therefore, highly desirable thata dry mounting tissue be found which will be useful after having beenkept for long periods of time. It is also desirable to find a mountingtissue which is operative at relatively low temperatures, to avoidpossible scorching of the prints by the use of a very hot iron, andwhich is operative over a relatively wide range of temperature, so thatthe temperature of the iron need not be so closely controlled inmounting the prints.

We have discovered that a dry-mounting tissue having all of thesedesirable characteristics can be prepared by coating paper with acomposition of nitrocellulose, tricresyl phosphate and shellac or othersuitable resin.

We prefer to use nitrocellulose of half-second viscosity, becausecompositions containing it soften at a lower temperature thancompositions containing nitrocelluloses of higher viscosity.Nitrocellulose of higher viscosity may be used when it is possible ordesirable to employ higher temperatures for the mounting.

The solvent mixture employed inpreparing and coating the adhesivecomposition must contain a solvent for the shellac or other resin, aswell as being a solvent for the nitrocellules and tricresyl phosphate.The solvent mixture which we prefer to use is a mixture of acetone andethyl alcohol, in the proportions of 20 to 50% of acetone less.

and to 50% of ethyl alcohol. The ethyl alcohol may, of course, bedenatured. Other solvent combinations may be used, such as mixtures ofethyl acetate and ethyl alcohol or mixtures of ethyl acetate, butylacetate and methyl, ethyl and 5 butyl alcohols, the particularcombination depending on the time of drying desired. The proportions ofthe active components of the adhesive composition which we prefer to useare as follows: nitrocellulose parts, tricresyl phosphate 10 to parts,shellac or other resin 10 to 200 parts. Even a smaller ratio of shellacor other resin may be employed although some is desirable. Theconcentration of the solution depends upon the method by which it is tobe coated upon the 1 paper in making the mounting tissue. If the paperis to be dipped into the solution, the concentration of nitrocelluloseshould be about 6 to 7% when half-second nitrocellulose is used, withthe tricresyl phosphate and shellac in the abovestated proportions tothe nitrocellulose. If the solution is to be spread on the paper, thenitrocellulose concentration should be about 16%.

Both sides of the paper are ordinarily coated with the solution.Suitable forms of apparatus for coating paper by dipping and byspreading are well known in the art. The solvents may be recovered ifdesired.

Dry mounting tissue made according to our invention has a working range,in mounting, of 0 about 200 to 240 F., whereas dry mounting tissue madeby merely impregnatingpaper with shellac has a working range of about240 to 255 F. It will, therefore, be seen that the working. range of ourproduct is both lower and wider than that of the dry mounting tissue nowin common use. The temperature at which our tissue is operative can bevaried by varying the proportions of the active components of theadhesive composition. The keeping qualities of our novel dry mountingtissue are far better than those of the tissue prepared by impregnatingpaper with shellac. At ordinary room temperatures it remains smooth, dryand flexible over long periods. of time. When subjected to acceleratedtesting. by being maintained at an elevated temperature, our novel drymounting tissue was still in good condition after flve times the periodrequired to render the old type-of dry mounting tissue use- 50 Otherresins which we' may use in place of shellac are ester gum, gum mastic,and dammar and the like. Dry mounting tissues prepared with these resinsaccording to our invention have beenfound to have working ranges of from210 to 55 300 F, By suitably varying the proportions of nitrocellulose,tricresyl phosphate and resin, the temperature at which adhesion can beeffected may be varied as desired.

While we have referred to paper as the support, it will be understoodthat we may use any type of paper, such, for instance, as tissue paper,yoshino paper, etc.,' and that we may also use cloth or other thinmaterial as the support. we may also make a mounting tissue without anysupport, by coating our composition on a plate, wheel, or other fiatcoating surface and stripping it therefrom although we' prefer, ofcourse, to employ one of the supports above named. 1

what we claim as our invention and desire to be secured by LettersPatent of the United States is:

l; A photographic dry mounting tissue consisting of paper coated on bothsides with a composition consisting essentially oi parts of low- 5viscosity nitrocellulose, from to parts 0! tricresyl phosphate, and from10 to 200 parts of shellac.

2. A photographic dry mounting tissue consisting of paper coated on bothsides with a com- 10

